1. Field of the Invention
The present invention relates to a method for processing a substrate and a substrate processing apparatus.
2. Description of the Related Art
In recent years, so-called turntable type film deposition apparatuses have been researched and developed as a film deposition apparatus that performs an ALD (Atomic Layer Deposition) method and the like. This film deposition apparatus includes a rotatable turntable on which a plurality of semiconductor wafers (which are hereinafter called “wafers”) that are objects to be processed is placed in a vacuum chamber (i.e., process chamber). There is a supply area of a reaction gas A and a supply area of a reaction gas B, and separation areas separating the supply areas from each other. The areas are separately provided above the turntable.
When the above film deposition apparatus performs a substrate processing step repeatedly, a reaction product derived from the reaction gases cumulatively attaches to an inner wall of the process chamber, a substrate holding unit in the process chamber and the like, and a cumulative film (a deposited film) is formed. When a film thickness of the cumulative film exceeds a predetermined thickness, sometimes a gas generated from the cumulative film during a film deposition process reacts with another gas, by which a substance that is not expected to be generated may attach to the wafers. Moreover, if the cumulative film is cracked or peeled, particles may be generated, and the wafers may be contaminated.
To solve this, Japanese Laid-Open Patent Application Publication No. 2008-283148 discloses a method of removing a reaction product attached to an inner wall of a process chamber, a substrate holding unit and the like by supplying a cleaning gas into the process chamber after a film thickness of a cumulative film exceeds a predetermined thickness.
However, when the film thickness of the cumulative film is thick, particles may be generated from film flakes of the cumulative film attached to the inner wall of the process chamber. In particular, when an oxide-based film such as a silicon oxide film or the like is deposited on wafers, the particles are more likely to be generated than when a nitride-based film such as a silicon nitride film or the like is deposited on the wafers. Because of this, when depositing the oxide-based film, a cleaning treatment needs to be performed more frequently than when depositing the nitride-based film, by which a period of time allocable to the film deposition process is shortened. Asa result, a PM (Preventive Maintenance) cycle that indicates a cycle of the preventive maintenance of a substrate processing apparatus becomes short, and a downtime of the substrate processing apparatus increases.